A transplanted kidney is rejected within minutes on the operating table. Biopsy shows fibrinoid necrosis of vessel walls and intravascular thrombosis. What is the mechanism of this rejection?
- A Preformed recipient antibodies against donor HLA antigens activate complement ✓
- B CD8+ cytotoxic T cells destroy graft cells directly
- C Recipient CD4+ T cells release cytokines causing graft vasculopathy
- D Natural killer cells recognize absence of self HLA on graft cells
Correct answer: A. Preformed recipient antibodies against donor HLA antigens activate complement
Explanation
Hyperacute rejection occurs within minutes to hours of revascularization and is caused by preformed recipient IgG antibodies directed against donor HLA class I or ABO blood group antigens. These antibodies bind to graft endothelium, activate complement via the classical pathway, and trigger platelet aggregation and thrombosis. Thorough cross-matching before transplantation has made this rare in clinical practice. It is irreversible and the graft must be removed.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.